The 4th World Happiness Report found Denmark is the happiest country – with the U.K. at 23.

The report found that people are happier living in societies where there is less inequality of happiness. Likewise it found that the bigger the gap - or inequality - in a country's happiness, the more widespread unhappiness is as a whole.

It also looked at social support - defined as being able to count on someone in difficult times - and the presence or otherwise of corruption.

"Human wellbeing should be nurtured through a holistic approach that combines economic, social and environmental objectives," Columbia University Earth Institute Director Jeffrey Sachs said in a SDSN press release.

"Rather than taking a narrow approach focused solely on economic growth, we should promote societies that are prosperous, just, and environmentally sustainable."